Scientists Cast Doubt on TSA Safety Tests of Full-Body Scanners
The Transportation Security Administration says its full-body X-ray scanners are safe. However,scientists with expertise in imaging and cancer say the evidence made public to support those claims is unreliable. And in a new letter sent to White House science adviser John Holdren, they question why the TSA won't make the scanners available for independent testing by outside scientists. The letter to the White House science adviser, signed by five professors at University of California, San Francisco, and one at Arizona State University, points out several flaws in the tests. Studies published in scientific journals in the last few months have also cast doubt on the radiation dose and the machines' ability to find explosives. "There's no real data on these machines, and in fact, the best guess of the dose is much, much higher than certainly what the public thinks," said John Sedat, a professor emeritus in biochemistry and biophysics at UCSF and the primary author of the letter. The trouble is that there is no ideal device for measuring the radiation dose given by backscatter X-rays, said David Brenner, director of the Columbia University Center for Radiological Research. The machines emit a pencil beam that rapidly moves across and up and down the body, he said. The TSA says that the scanners have safety systems, such as automatic shutoffs and emergency stop buttons, that will kill the beam in the event of any problem that could result in abnormal radiation. How those fail-safe systems work isn't entirely clear. When Johns Hopkins researchers visited the Rapiscan facility, the automatic termination appeared to work. But the full results of the shutoff tests are redacted. What's more, the system didn't have an emergency stop button. READ ENTIRE ARTICLE
The Transportation Security Administration says its full-body X-ray scanners are safe. However,scientists with expertise in imaging and cancer say the evidence made public to support those claims is unreliable. And in a new letter sent to White House science adviser John Holdren, they question why the TSA won't make the scanners available for independent testing by outside scientists. The letter to the White House science adviser, signed by five professors at University of California, San Francisco, and one at Arizona State University, points out several flaws in the tests. Studies published in scientific journals in the last few months have also cast doubt on the radiation dose and the machines' ability to find explosives. "There's no real data on these machines, and in fact, the best guess of the dose is much, much higher than certainly what the public thinks," said John Sedat, a professor emeritus in biochemistry and biophysics at UCSF and the primary author of the letter. The trouble is that there is no ideal device for measuring the radiation dose given by backscatter X-rays, said David Brenner, director of the Columbia University Center for Radiological Research. The machines emit a pencil beam that rapidly moves across and up and down the body, he said. The TSA says that the scanners have safety systems, such as automatic shutoffs and emergency stop buttons, that will kill the beam in the event of any problem that could result in abnormal radiation. How those fail-safe systems work isn't entirely clear. When Johns Hopkins researchers visited the Rapiscan facility, the automatic termination appeared to work. But the full results of the shutoff tests are redacted. What's more, the system didn't have an emergency stop button. 
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